1. Field of the Invention
This invention relates to a method of and an apparatus for inspecting conditions of parts of electrical ignition type engines.
2. Description of the Prior Art
Engine-scopes have heretofore been used for the purpose of conducting adjustment or reparation of electrical ignition type engines. Such engine-scopes comprise a cathode-ray tube for visually displaying primary ignition waveforms, secondary ignition waveforms and so on, which may represent conditions of parts of engines such as the conditions of the ignition system and the conditions of mixed gas within the cylinder.
FIG. 1 of the accompanying drawings schematically illustrates the ignition system of a four-cylinder engine comprising a battery 20, an ignition coil 21, a capacitor 22, a contact 23, a distributor 24 and ignition plugs 25. The primary ignition waveform may be defined as the change in the potential difference between a point A and ground plotted with respect to time, and the secondary ignition waveform may be defined as the change in the potential difference between a point B and ground plotted with respect to time. FIG. 2(a) illustrates normal and abnormal primary ignition waveforms, and FIG. 2(b) normal and abnormal secondary ignition waveforms.
Such conventional engine-scopes require an operator who has memorized a set of normal waveforms. The operator must judge whether a waveform displayed on the engine-scope is normal or abnormal, in the light of the set of normal waveforms in his memory. Furthermore, even if he finds that the waveform is abnormal, it is very difficult for him to judge what part of the engine is defective because he would have to make many comparisons between the abnormal waveform and a number of standard abnormal waveforms before he can find one of the standard waveforms which is most similar to the displayed abnormal waveform. For this reason, only those much skilled in the art can master such conventional engine-scope.
It is an object of this invention, therefore, to provide a method of and an apparatus for inspecting conditions of parts of electrical ignition type engines which method and apparatus eliminate the above-mentioned disadvantages and permit any operator to easily, accurately and objectively judge whether an actual waveform taken from an engine is normal or abnormal.